The word itself strikes fear into many Canadians and for close to a million people, it is a stark and terrifying reality. Cancer, above almost any other disease, has proven itself to be a scourge on public health. The sudden transformation of normal human cells into tumours that can not only grow, but spread, is one of science's great mysteries that have yet to be completely solved.
Over the last few years, the impact of germs on the development of cancer has been researched and the results have been disconcerting. The direct relationship between several cancers and viruses have already been established and there is increasing evidence to show that the totality of germs in and on the body -- the microbiome -- can contribute to the development of several oral and gastrointestinal cancers as well as prostate and even breast cancer. On the flip side, other researchers have examined how good germs may help to prevent cancers. Evidence has shown that a healthy gut microbiota can prevent and stall liver and colorectal cancers.
While the links between germs and cancer continues to be a hot topic in research, the actual mechanism has been known for quite some time. Several cancers are an unfortunate consequence of a much more devious and for the most part unseen health ailment, chronic, low-level inflammation. In the inflammatory process, the body creates a number of chemicals, such as free radicals, that can help to fight off infection and other chronic problems. But these same chemicals also affect normal cells and as a result, may injure them or change them in such a way that they become abnormal. Should that happen, the cells may transform and become immortal. When they do, they start to take over the microenvironment and lead to the development of a tumour.
In a healthy individual, the microbiome is in balance with the rest of the body and there is little to no inflammation. But if that balance is disturbed, either through infection, antibiotic use, dietary changes and poor lifestyle, then the body goes into an inflammatory state. Most people won't notice this change as there are no outward symptoms. But inside, the immune system is chugging away, producing free radicals and other inflammatory chemicals that can injure normal cells and form tumours.
This link between an imbalanced microbiome, inflammation, and cancer has led to several attempts to find out whether good germs can act as not only balancers but also cancer fighters. Two years ago, a duo from Lund University in Sweden explained how probiotics are indeed useful in preventing chronic inflammation not only in the gut but also throughout the body. In the same year, a team from China and the United States suggested that probiotics may be specifically helpful in preventing colorectal cancer. Earlier this year, a team from Finland highlighted one specific mechanism of cancer formation -- and avoidance -- involving bacteria, the immune system and the onset of tongue cancer. By avoiding the bacteria identified in the study, one could improve their chances to avoid this particular disease.
While this information may be good for those not living with cancer, the data could not offer much to those who were suffering not only from the disease, but also the treatment. Chemotherapy, which is usually the first line of defense, can have some fairly dramatic consequences on the body. One of the worst problems is a change in the gut microbiota leading to diarrhea, mucositis, and unfortunately, more inflammation.
While the overall success of chemotherapy is rising, the challenge of the double-edged sword with respect to the immune system has led scientists to wonder if the side effects can be resolved by good germs. Last week, the answer was revealed -- at least in mice.
Two articles by large collaborations of researchers examined how good bacteria are involved in general chemotherapy as well as treatment with a specific chemical, cyclophosphamide. Both studies looked at the effect of having a balanced microbiota as well as one that is imbalanced through the use of good germs-killing antibiotics. The results showed that the presence of probiotic species such as Lactobacillus improved the overall balance of the immune system and helped to keep inflammation at bay. But when these species were not present, the effects were not only harmful in the short term; they also triggered a long term immune dysfunction that could make things worse for the mouse.
Neither study concluded that probiotics should be given to patients receiving chemotherapy, yet the results suggest that this recommendation may not be too far away. With future clinical trials, the results of this study should be seen in humans. We know the role of good germs in maintaining health is established; this should also apply here.
Should this postulate become reality, those who are suffering from cancer will once again be able to view microbes positively. While germs may have contributed to the plight; they can redeem themselves by helping individuals ultimately win the fight.
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